吴起县耕地面积变化对其产业结构影响

为研究吴起县耕地面积的影响因素，尤其是退耕还林政策实施后的影响因素变化情况，基于吴起县1949－2007年统计资料，以主成份分析法对耕地面积的变化进行了分阶段的分析，并对当地的耕地影响因素的变化趋势和产业结构情况进行了研究。结果显示耕地的影响因子越来越趋向于复杂化，包括全部信息所需要选取的主成份越来越多，但退耕还林政策的实施后，包括全部信息所需选取的主成份减少；耕地面积的第一主成份影响因素贡献率呈现增长的趋势，分别为54.315%、52.857%、70.158%、82.704%。目前吴起县耕地面积的变化受退耕还林政策的实施力度影响很大，并且当地经济对石油产业的依赖性过大。

Effect of farmland area variation on industrial structure in Wuqi county

Principal component analysis (PCA) was used to analyze of Wuqi County statistics ranging from 1949 to 2007 to identify the main drivers of variations in cultivation, especially after the implementation of the Grain for Green program. The analysis examined the stages in cultivated land use, impact trends, and changes in the industrial structure. Results showed that, from 1949 to 1998, the main factors affecting farmland area became increasingly complicated and the number of principal components needed for analysis increased; however, with the implementation of Grain for Green in 1999, the components needed for analysis decreased. The contribution of the first principal component increased over time from 54.315% to 82.704%. The Grain for Green program can greatly influence farmland and local economies may depend too much on the hydrocarbon industry.